The invention relates to a phosphoric acid fuel cell and more particularly to a phosphoric acid fuel cell with a replenishment electrolyte feed to a cell matrix from the cathode side where the cathode is smaller than the anode to prevent corrosion of the cathode side of the fuel cell.
When operating, phosphoric acid fuel cells experience electrolyte losses due to volume changes caused by changes in operating parameters, absorption by plates, and normal evaporation. The cells incorporate an electrolyte replenishment feed to each cell to accommodate these changes and allow continuous operation of the cells over extended periods of time. The electrolyte feed system, herebefore used, has resulted in corrosion damage of the cathode and its interface with the bipolar plate where they overlap the anode, because it is necessary expose the matrix to the electrolyte in the acid grooves in the margins of the long sides of the fuel cell to maintain adequate electrolyte in the fuel cells. The acid supply grooves of such systems were put in the anode side of the bipolar plates so that the acid supply would wick directly into the matrix at the center of the cell and not through the back of the cell.